The article attempts to present the history of the parish church and burial cemetery in Tykocin on the basis of the notes found in the Books of Dead (Libri Mortuorum) from 1717-1795, stored in the archive of the Roman Catholic Parish in Tykocin. Researchers of Tykocin history and Tykocin parish have not used the Books of Dead yet to reproduce the topography and architecture of the church estate. Whereas on the basis of the information about burial places of deceased parishioners, many details regarding the church architecture, interior furnishing, a kind of buildings around the church, and a layout of the burial cemetery may be reconstructed. Moreover, the Books of Dead provide information about building and renovating works carried out near the church as well as such incidents as fires and other disasters. As far as credibility is concerned, such information deserves attention since it was not its author's intention to just write it down for any pur-pose but to merely support orientation in the cemetery's topography. The church,nearby constructions, cemetery objects and houses located in the church plot are in these documents points of reference to determine a location of certain graves. Following this trail, the author of this article attempted to establish a precise date and circumstances of the parish church's fire in Tykocin which was functioning before the construction of a new monumental baroque church in 1742-1750 by the landlord of Tykocin estate - Jan Klemens Branicki, which exists until today. In the subject literature so far a still prevailing opinion says that the great fire which destroyed a wooden parish church and the town's centre in 1741 could be a possible impulse to build a new baroque church and rebuild Tykocin's downtown. In result of the analysis of the entries made in the Books of Dead the author of this article has successfully acknowledged that the wooden parish church built before 1717, then renovated and improved in the 1720s-1730s, did not burn in the 1741's fire but six years later, between 27th April and 24th July 1747. It sheds new light on the history of Tykocin's reconstruction by Jan Klemens Branicki allowing to assume that the old church's fire was not an impulse but merely hastened nishing of new foundation that had been planned before notwithstanding the fact of a previous parish church building's existence.